From a065f8ed355f08131c39787b4c7a41543ff643b3 Mon Sep 17 00:00:00 2001
From: Serhey Popovych <serhe.popovych@gmail.com>
Date: Fri, 29 Nov 2019 11:21:32 +0200
Subject: em_ipset: Build on old kernels

Make sure TCF_EM_IPSET defined and corresponds to current upstream value
if not defined in target kernel. You need iproute2 version that supports
em_ipset to communicate correctly. Include ip_set_compat.h after
pkt_cls.h to prevent TCF_EM_IPSET redefine error.

Detect skb->iif => skb->skb_iif rename after commit 8964be4a9a5c ("net:
rename skb->iif to skb->skb_iif").

Add dev_get_by_index_rcu() define pointing to __dev_get_by_index() to
build on RHEL6 kernels with explicit note that this may not work on all
architectures.

Always build em_ipset regardless of CONFIG_NET_EMATCH_IPSET option.

Signed-off-by: Serhey Popovych <serhe.popovych@gmail.com>
Signed-off-by: Jozsef Kadlecsik <kadlec@netfilter.org>
---
 configure.ac                                            | 11 +++++++++++
 kernel/include/linux/netfilter/ipset/ip_set_compat.h.in | 17 +++++++++++++++++
 kernel/net/sched/Kbuild                                 |  2 +-
 kernel/net/sched/em_ipset.c                             |  2 +-
 4 files changed, 30 insertions(+), 2 deletions(-)

diff --git a/configure.ac b/configure.ac
index 17ba184..e3ddcce 100644
--- a/configure.ac
+++ b/configure.ac
@@ -554,6 +554,17 @@ else
 	fi
 fi
 
+AC_MSG_CHECKING([kernel source for iif to skb_iif rename in struct sk_buff])
+if test -f $ksourcedir/include/linux/skbuff.h && \
+   $AWK '/^struct sk_buff {/,/^};$/' $ksourcedir/include/linux/skbuff.h | \
+   $GREP -q 'skb_iif'; then
+	AC_MSG_RESULT(yes)
+	AC_SUBST(HAVE_SKB_IIF, define)
+else
+	AC_MSG_RESULT(no)
+	AC_SUBST(HAVE_SKB_IIF, undef)
+fi
+
 AC_MSG_CHECKING([kernel source for struct net in struct xt_action_param])
 if test -f $ksourcedir/include/linux/netfilter/x_tables.h && \
    $AWK '/^struct xt_action_param /,/^}/' $ksourcedir/include/linux/netfilter/x_tables.h | \
diff --git a/kernel/include/linux/netfilter/ipset/ip_set_compat.h.in b/kernel/include/linux/netfilter/ipset/ip_set_compat.h.in
index 92d815e..d71c3fd 100644
--- a/kernel/include/linux/netfilter/ipset/ip_set_compat.h.in
+++ b/kernel/include/linux/netfilter/ipset/ip_set_compat.h.in
@@ -51,6 +51,7 @@
 #@HAVE_SYNCHRONIZE_RCU_BH@ HAVE_SYNCHRONIZE_RCU_BH
 #@HAVE_LOCKDEP_NFNL_IS_HELD@ HAVE_LOCKDEP_NFNL_IS_HELD
 #@HAVE_COND_RESCHED_RCU@ HAVE_COND_RESCHED_RCU
+#@HAVE_SKB_IIF@ HAVE_SKB_IIF
 
 #ifdef HAVE_EXPORT_SYMBOL_GPL_IN_MODULE_H
 #include <linux/module.h>
@@ -430,5 +431,21 @@ static inline u16 nfnl_msg_type(u8 subsys, u8 msg_type)
 #define SIZE_MAX	(~(size_t)0)
 #endif
 
+#ifndef TCF_EM_IPSET
+#define TCF_EM_IPSET 8
+#endif
+
+#ifndef HAVE_SKB_IIF
+#define skb_iif iif
+#endif
+
+#ifndef HAVE_DEV_GET_BY_INDEX_RCU
+/* This should not be considered RCU-safe on all architectures.
+ * You probably should consider upgrading your kernel in case of
+ * kernel crashes including em_ipset and this function call.
+ */
+#define dev_get_by_index_rcu __dev_get_by_index
+#endif
+
 #endif /* IP_SET_COMPAT_HEADERS */
 #endif /* __IP_SET_COMPAT_H */
diff --git a/kernel/net/sched/Kbuild b/kernel/net/sched/Kbuild
index 6d8e8d6..e93476c 100644
--- a/kernel/net/sched/Kbuild
+++ b/kernel/net/sched/Kbuild
@@ -1,4 +1,4 @@
 NOSTDINC_FLAGS += -I$(KDIR)/include
 EXTRA_CFLAGS := -DCONFIG_IP_SET_MAX=$(IP_SET_MAX)
 
-obj-$(CONFIG_NET_EMATCH_IPSET) += em_ipset.o
+obj-m += em_ipset.o
diff --git a/kernel/net/sched/em_ipset.c b/kernel/net/sched/em_ipset.c
index bd9566f..96fd4a3 100644
--- a/kernel/net/sched/em_ipset.c
+++ b/kernel/net/sched/em_ipset.c
@@ -15,10 +15,10 @@
 #include <linux/string.h>
 #include <linux/skbuff.h>
 #include <linux/netfilter/xt_set.h>
-#include <linux/netfilter/ipset/ip_set_compat.h>
 #include <linux/ipv6.h>
 #include <net/ip.h>
 #include <net/pkt_cls.h>
+#include <linux/netfilter/ipset/ip_set_compat.h>
 
 #ifdef HAVE_TCF_EMATCH_OPS_CHANGE_ARG_NET
 static int em_ipset_change(struct net *net, void *data, int data_len,
-- 
cgit v1.2.3